Process for transporting sulfur through pipelines



May 13, 1969 F. L. MEYER "ETAL 3,443,337

PROCESS FOR TRANSPORTING SULFUR THROUGH PIPELINES Filed Aug. 28. 1967 Sheet of 2 SECONDARY LIQUID PRIMARY LIQUID WATER- WATERQ HYDROCARBON WASH HYDROCARBON 1 7 WASH 6 4 5 I I 7 luoulo I 7 8 7 uvoaocmaou 50 5b 5c CENTRIFUGE MOLTEN 2 6o %w I m LINE SULFUR- SULFUR ,1 XER OIL ZLZZZT' 9' UQU'D PIPELINE HYDROCARBON I0 WATER SEPARATOR WATER*\ FIG.

250 F MOLTEN SULFUR 26 '9) 20 23 I COOL 5 I CENTRIFUGE :QZS WATER Q F 2|3 F I5 PSIA I5 PSIA /SLURRY PREP. 23 UNIT PUMP 27 CRUDE on. 32

BLENDER, SLURRY as F FLASHER 2o PSIA F |9mm Hg SLURRY OF PUMP SULFUR IN CRUDE on. PIPELINE FIG. 2

THEIR AGENT 1969 F. L. MEYER ETAL 3,443,837

PROCESS FOR TRANSPORTING SULFUR THROUGH PIPELINES Filed Aug. 28. 1967 Sheet 3 of 2 CRUDE OIL 43 4s T 0 I I 47 F WATER CAKE 44 SLURRY BLENDER RECEIVER FLASHER 2|3 F 70F 250 F MOLTEN SULFUR lO-7O SLURRY 3 OF SULFUR IN WATER-SULFUR SLURRY CRUDE SUPPLY FROM REMOTE AREA 67) IWATER DISPOSAL so 64 f r SEPARATING UNIT HYDROCARBON SUPPLY FROM CHAMBFR 63 REMOTE AREA \68 6| x70 69 LSULFUR-HYDROCARBON HYDROCARBON SLURRY READY FOR SLURRY PIPELINE TRANSPORT FIG. 4 70 {WATER DlSPOSAk SULFUR- 73 (/76 79 WATER MIXING 75 lS EPARATING UNIT 7 CHAMBER 72 R 80 SLURRY 7 P82 8| (SULFUR-HYDROCARBON GATHERING HYDROCARBON HYDROCARBON RY I EL NE SYSTEM SUPPLY FIG. 5

INVENTORSI FRANK L. MEYER L. PHILIP REISS PAUL E. TITUS AGENT Unite 3,443,837 PROCESS FOR TRANSPORTING SULFUR THROUGH PIPELINES Frank L. Meyer, Lewis Philip Reiss, and Paul E. Titus, Houston, Tex., assignors to Shell Oil Company, New York, N.Y., a corporation of Delaware Filed Aug. 28, 1967, Ser. No. 663,755 Int. Cl. B65g 53/30 US. Cl. 302-14 7 Claims ABSTRACT OF THE DISCLOSURE Background of the invention The transportation of sulfur as a water or oil slurry in pipelines is well known in the art. The sulfur may be sprayed in molten form into either water or a liquid hydrocarbon to form a slurry suitable for transportation though a pipeline. Formation of a stable slurry wherein the solid does not undergo any undesirable change or the slurry does not exhibit a tendency to wide variation in viscosity is essential to the process in addition to other problems which may be encountered during and after transportation of the slurry through a pipeline. Thus, separation of the solid from the carrier fluid, plating or coating of the solid on pipeline walls, plugging of the pipeline, corrosion, viscosity changes of the slurry requiring changes in pumping power which increases operation costs, etc., are only a few of the problems normally encountered in transporting solid slurries through pipelines.

Although the above are some of the serious problems for consideration of transporting solids and in particular sulfur through pipelines, nevertheless the transportation of sulfur in slurry form through pipelines can be an economic, effective and attractive means of transportation, particularly since sulfur is recovered or obtained from isolated, remote and inaccessible areas, and must be transported to desired areas. As noted above, a number of methods have been proposed in the pipeline transportation art to accomplish this end such as injecting molten sulfur into water or a liquid hydrocarbon thereby forming a sulfur slurry for pipeline transportation. Such means for transporting sulfur generally do not overcome the corrosion, coating and/or plugging problems noted above.

It is another object of the present invention to transport sulfur as a slurry through pipelines.

Still another object of the present invention is to transport through a pipeline sulfur slurries without causing coating, deposition, plugging or corrosion of the pipeline.

Still another object of this invention is to form a slurry of sulfur by means of phase transfer from a non-wetting liquid, e.g., an aqueous medium, into a wetting medium, e.g., a liquid hydrocarbon medium, which latter sulfur slurry when so formed is stable, non-corrosive and does not tend to cause pipeline plugging when said slurry is transported through a pipeline and from which the sulfur can be readily recovered as essentially pure sulfur.

3,443,837 Patented May 13, 1969 ice The present invention is directed to an improved, novel and new technique for preparing a sulfur slurry for pipeline transportation over great distances by first forming a sulfur-aqueous liquid (Water) slurry and thereafter phase transferring the sulfur particles from the aqueous liquid into a liquid hydrocarbon, injecting the sulfur-hydrocarbon slurry into a pipeline and transporting it to a terminal station at which end the sulfur is recovered from the liquid hydrocarbon carrier. The essence of the present invention resides in the discovery that by forming sulfurhydrocarbon slurries by phase transference of sulfur particles formed by first injecting molten sulfur into an aqueous liquid, e.g., water, essentially uniform spherical particles having desired dimensions of sulfur are formed which on subsequent phase transfer into a liquid hydrocarbon, such as a petroleum crude oil or fractions thereof, maintain their shape and particle size and form a stable sulfur-hydrocarbon slurry which is resistant to separation. In addition, it has been found that sulfur from sulfur slurries formed by the phase transfer method of the present invention is more easily recovered from the hydrocarbon carrier When using conventional separation techniques such as solvent extraction, filtration or other methods and the final recovered sulfur product is pure and bright and is essentially or wholly free of the liquid hydrocarbon carrier. In carrying out the process of the present invention it is essential that the sulfur particles be transfered from the aqueous (water) phase to the liquid hydrocarbon (oil) phase and not vice versa since the phase transfer has a highly directional toward the oil/sulfur slurry. Contacting an oil/sulfur slurry with water can result in formation of an emulsion from which the sulfur is difiicult to separate.

The final sulfur oil slurry prepared by the process of the present invention can contain from 1% to or more percent by weight (preferably from 20% to 60%) of sulfur particles (1-2500 microns, preferably between 1 and 1000 microns) suspended in a petroleum hydrocarbon such as crude oil or a condensate or fractions thereof having a .boiling range from below that of kerosene to that approaching crude oil.

Description of the preferred embodiments According to the present invention, molten sulfur preferably at a temperature of between 240 and 320 F., preferably between 250 and 300 F., is injected into an aqueous liquid such as water. The aqueous liquid may be cold or hot and generally it can be cold and the amount of sulfur dispersed therein can vary over a wide range such as from 1 to 75% or higher. Injection of the molten sulfur into the aqueous liquid, e.g., water, under pressure has been found to result in the formation of uniformly spherical sulfur particles having an average siZe of 10-750 microns. The sulfur-aqueous slurry is then contacted with a liquid hydrocarbon so as to effect phase transfer of the sulfur particles from the aqueous phase into the liquid hydrocarbon phase. By means of this process, agglomeration of sulfur particles in the liquid hydrocarbon phase normally encountered when molten sulfur is dispersed directly into a liquid hydrocarbon as described in US. Patent 2,798,772 is prevented and the sulfur particles of desired particle size remain stably dispersed in the hydrocarbon slurry while being transported through a pipeline to a terminal station. The prevention of sulfur agglomeration into a sticky-tacky mass by the process of the present invention is essentially alleviated.

Spraying molten sulfur into Water produces glassy, spherical particles of sulfur having better rheological properties than with angular crystalline sulfur particles formed when molten sulfur is sprayed directly into a liquid hydrocarbon and which tends to go into a sticky-tacky stage which is very undesirable. The phase transfer of the sulfur particles from the aqueous phase to the hydrocarbon phase to form a sulfur-hydrocarbon slurry is essential since spraying molten sulfur into water has been found to inhibit particle growth due to agglomeration of the tacky sulfur particles.

The method of dispersing sulfur in an aqueous liquid such as water can be accomplished by any suitable means such as described in US. Patents 1,969,242, 2,190,922, 2,658,016, 2,917,345 and 2,947,578. The aqueous slurry containing from 20 to 60% sulfur particles can be filtered or contacted directly with a liquid hydrocarbon to effect phase transfer of the sulfur particles from the aqueous phase to the hydrocarbon phase. The sulfur-hydrocarbon slurry is then injected into a pipeline for transportation to a terminal station at which point the sulfur is recovered by suitable means from the hydrocarbon and both products, namely the sulfur and hydrocarbon purified if necessary by solvent extraction or the like. Suitable means for purifying the recovered sulfur from the hydrocarbon carrier can be accomplished by suitable means described in US. Patents 2,798,772, 2,809,885 and 3,042,503 while the liquid hydrocarbon can be desulfurized if necessary by such means as described in US. Patents 1,971,172, 2,930,750 and 3,163,593 or any other suitable means.

Brief description of the drawing The invention can be further understood from the following fiow diagrams. Referring to flow diagram FIGURE 1 molten sulfur at 300 F. and 40 p.s.i. from line 1 is injected or sprayed into mixing chamber 2 into which water at 50 F. and 60 p.s.i. from line 3 is also injected and the two materials are mixed in mixer 2 to form a 2060% sulfur-Water slurry.

The slurry is conducted via line 4 into a chamber, e.g., a centrifuge 5, consisting of three (or more) partitioned sections 5a, 5b and 50. Water is removed from chamber section 5a through line 6 and discarded or recycled into mixer 2 via lines 14 and 14a, or into line 3 via lines 14 and 14b.

The dewatered sulfur moves to chamber section 5!) Where it is contacted with recycled liquid hydrocarbon removed from chamber section 5c via line 13. The oil, containing small amounts of water, is removed from chamber 5b via line 9 and conducted into separator 10 where Water is removed via line 11, and the oil removed via line 12 and injected into line 7.

The sulfur moves to chamber section 5c where it is contacted with fresh liquid hydrocarbon introduced via line 7. The phase transferred sulfur is conducted from chamber section 5c to a mixer via line 8. Liquid hydrocarbon is added to a conventional in-line mixer 16 via line 7a to obtain the desired sulfur/ oil ratio. The sulfuroil slurry is then conducted to pipeline for transportation to a terminal station for separation of the sulfur from the oil.

Other flow diagrams of forming sulfur slurries by the process of the present invention are shown in FIGURES 2 and 3. In FIGURE 2 Water at 70 F. from line 19 and molten sulfur at 250 F. from line 20 are conducted into a slurry preparation unit 21 having variable shear orifices to form a slurry which is conducted via line 22 into a centrifuge 23 operating at 213 F. and 15 p.s.i.a. The aqueous phase is removed via line 24 having pump 25 and pumped back into dispersion pump 21. The sulfur mud is removed via line 23a into cake receiver 26 where additional moisture is removed and the sulfur mud .4 conducted via line 27 into slurry flasher 28 from which a concentrated sulfur mud is conducted via line 29 and pump 30 into blender 31 where a liquid hydrocarbon, e.g., crude oil, is injected via line 32 and the oil-sulfur slurry removed via line 33 'wtih the aid of pump 34 and injected into pipeline 35 for transportation to a terminal station. The aqueous phase from blender 31 can be removed via line 36.

Another flow diagram is shown in FIGURE 3 where Water at 70 F. from line 40 and molten sulfur from line 41 is pumped through pump 42 are slurried and charged into a cake receiver 43 to form a sulfur mud which is conducted via line 44 into a slurry flasher 45 where substantial amounts of moisture are removed via line 46 and the concentrated sulfur mud conducted into blender 47 via line 48 and pump 49 where crude oil at about 70 F. is injected and from which a 20-60% slurry of sulfur in crude oil is removed via line 48 and pumped through pump 51 into pipeline 52 for transportation to a terminal station for recovery of the sulfur from the oil.

Still another flow diagram is shown in FIGURE 4 wherein a sulfur-Water slurry is formed by injecting molten sulfur into water and the mixture is pumped through line 60 and a hydrocarbon pumped through line 61 both coming from remote areas are injected into a mixing chamber 62 and the total mixture conducted through line 63 into a separating unit 64 to allow for the sulfur to be phase transfered into the hydrocarbon phase and form a sulfur-hydrocarbon slurry and a water phase which is disposed via line 67. The sulfur-hydrocarbon slurry is removed from separator 64 via line 68 and injected into pipeline 69 for transportation to a terminal station. If more hydrocarbon is desired it can be introduced into line 68 and/or 69 via line 70.

A still further modification of this process as shown in FIGURE 5 is to form a sulfur-water slurry as above at various points and pumping them thorugh various lines 70, 71 and 72 into a mixing chamber 73. A hydrocarbon supply is conducted into the chamber 73 via line 74 and the entire resultant mixture is conducted through line 75 into separating unit 76 to allow for the sulfur-hydrocarbon slurry and a water phase which is dispersed via line 79. The sulfur-hydrocarbon slurry is removed from separator 76 via line 80 and sulfur-hydrocarbon slurry is removed from separator 76 via line 80 and injected into pipeline 81 for transportation to a terminal station. If more hydrocarbon is desired, it can be introduced into line 80 and/ or 81 via line 82.

The invention is illustrated by the following examples of forming sulfur slurries by phase transfer of sulfur from a non-wetted aqueous liquid to a wetted-hydrocarbon liquid for pipeline transportation.

Example I Molten sulfur at 300 F. and 40 p.s.i. and water at 50 F. and 60 p.s.i. was pumped into a mixer to form a 46% sulfur-water slurry of spherically shaped particles having particle size distribution shown in Table I.

TABLE I.--PAR'IICLE SIZE DISTRIBUTION Sieve size, microns Percent retained Percent abov 20 Below 20..

The sulfur-water slurry was centrifuged to remove the bulk of the water and form a sulfur cake. The sulfur cake was washed several times with kerosene thereby freeing the cake of entrained water and thereafter the kerosene washed sulfur, containing traces of water up to 2% weight, was suspended into kerosene to form a 50% sulfur-kerosene slurry and the slurry injected into a pipeline for transportation to a terminal station. During its transportation the pipe walls were clean and no sticking or plugging of the pipeline was observed.

Example II Molten sulfur at 250 F. and 60 psi. was dispersed into water at 50 F. to form a 50% sulfur slurry which slurry was filtered to form a sulfur cake. The cake was washed with crude oil and the cake was diluted with crude oil at about 70 F. to form a 30% slurry of sulfur in the crude oil and 0.51.0% NaOH basis residual water content was added. The slurry was pumped into a pipeline for transportation to a terminal station. No plugging or excessive corrosion of the line was observed.

Example III Molten sulfur at 300 F. and 40 p.s.i. was dispersed into water at 50 F. to form a 50% slurry of sulfur in water. The slurry was injected into a blender into which was injected an aromatic hydrocarbon oil at about 70 F. and the entire mass was agitated for a time suflicient to effect phase transfer of the sulfur into the oil phase. The water phase was removed and the sulfur-oil slurry was treated to remove entrained water and the slurry containing 40% sulfur in oil was injected into a pipeline for transportation to a terminal station.

Yellow sulfur can be recovered from the oil slurry by filtration, washing, melting, filtration of molten sulfur and liquid-liquid extraction with a hydrocarbon solvent containing 50% aromatic. Thus, at the receiving terminal the sulfur slurry can be filtered and washed. The recovered sulfur is then melted and purified by liquid-liquid extraction with an aromatic hydrocarbon such as cumene. Also, if desired the filtered sulfur can be steam stripped to recover bright yellow sulfur.

The foregoing description of the invention is merely intended to be explanatory thereof. Various changes in the details of the described methods may be made within the scope of the appended claims without departing from the spirit of the invention.

We claim as our invention:

1. A method for transporting sulfur through a pipeline to a terminal comprising:

injecting molten sulfur into an aqueous liquid medium to form a slurry mixture of sulfur particles in the aqueous liquid medium;

mixing a liquid hydrocarbon into the slurry mixture of sulfur in the aqueous liquid medium; maintaining the resultant mixture for a time sufficient to effect phase transfer of the sulfur particles from the aqueous phase to the hydrocarbon phase;

separating the sulfur-hydrocarbon phase from the aqueous phase; and

flowing the sulfur-hydrocarbon slurry into a pipeline for transportation to a terminal station.

2. The method of claim 1 wherein prior to effecting the phase transfer essentially all of the aqueous medium is removed.

3. The method of claim 1 wherein, prior to mixing the liquid hydrocarbon with the slurry of sulfur in the aqueous medium, the slurry is filtered to substantially remove the aqueous medium and the sulfur cake formed is blended with the hydrocarbon to form the sulfur-hydrocarbon slurry.

4. The method of claim 1 wherein the aqueous medium is water and the liquid hydrocarbon is a crude oil.

5. The method of claim 4 wherein the sulfur content of the hydrocarbon slurry is at least 20% by weight.

6. The method of claim 1 including the additional steps of:

recovering hydrocarbon slurry; and,

extracting with an aromatic hydrocarbon solvent to purify the sulfur.

7. A method for transporting sulfur through a pipeline to a terminal comprising:

injecting smolten sulfur into an aqueous liquid to form a slurry mixture of sulfur particles in the aqueous liquid medium;

pumping sulfur aqueous slurry mixture through a pipeline for some distance;

injecting the sulfur-aqueous liquid slurry into a pipeline containing a liquid hydrocarbon;

flowing the entire mixture in the pipeline for a time suflicient for the sulfur to phase transfer into the liquid hydrocarbon;

disposing the aqueous liquid from the pipeline; and,

maintaining flowing the sulfur-liquid hydrocarbon slurry to a terminal station.

References Cited UNITED STATES PATENTS 2,798,772 7/1957 Redcay 30214 2,917,345 12/1959 Phillips et al 30266 2,947,578 8/1960 Corneil et al. 30266 3,359,040 12/1967 Every 30214 ANDRES H. NIELSEN, Primary Examiner.

U.S. Cl. X.R. 

